Fiber Optic Linear Heat Detector (LHD)

1. The Linear Heat Detection System shall use RAMAN based Optical Time Domain Reflectometry (OTDR) technology
that includes the Fiber Optic Sensor Cable and a Linear Heat Detector (LHD) instrument that houses the opto-
electronics.

2. The sensor cable containing the optical fibers shall be connected to the LHD instrument in a single continuous
loop (Class A) to ensure redundancy and full coverage of the protected fire zones, even if the cable is broken / cut
/ damaged at one point.

3. Alternatively, the cable shall be connected on either end to a single LHD instrument, for full redundancy even if
the cable is broken / cut / damaged at one point or in case of a LHD instrument failure.

4. Suitable stainless steel armored fiber optic sensor cable or dielectric (metal-free) fiber optic sensor cable shall be
used. Either cable shall have Flame Retardant Non-Corrosive (FRNC) jacket. The sensor cables shall be integral
part of the system’s certifications for use as a fire detector (VdS, UL, FM).

5. The sensor cables shall be tested and approved for functional integrity for two hours at flame temperatures up to
750 °C according to IEC 60331-25.

6. Furthermore, the sensor cables shall be tested and approved against vertical flame propagation (IEC 60332-1, -2
and -3-24), gas evolvement during combustion (IEC 60754-1 and -2) and smoked density under combustion (IEC
61034-2).

7. The system shall provide continuous heat detection and temperature monitoring over the entire length of up to
10 km. A fire alarm condition or cable break shall be indicated and located precisely.

8. The LHD instrument shall provide one, two or four measurement channels, according to the design.

9. The LHD instrument must provide an integrated multi-color display to allow a comprehensive overview about the
instrument settings (IP-Address, Firmware, Instrument Type and Serial Number) as well as status and alarm
conditions (Alarm Zone, Alarm Location, Fiber Break Position, System Status).

10. The system shall be fully programmable with respect to zone lengths and alarm thresholds. Alarm thresholds shall
be set to fixed temperature, deviation from zone average and/or rate-of-rise (temperature gradient), for which a
confirmation cycle shall be configurable, to eliminate the risk of false alarms.

11. The LHD instrument shall have 44 volt-free, non-latching, certified relay outputs. One contact shall signal in case
of a system fault and the remaining 43 contacts shall be assignable to the zones (fire alarm and/or fiber break).

12. The LHD instrument shall have four embedded, opto-decoupled programmable input relays to reset alarms.

13. The LHD instrument must operate on a proven Real Time Operating System (RTOS), such as VxWorks, to ensure
safe operation in safety critical applications. Windows OS as well as any PC required for system operation is not
acceptable.

14. The LHD instrument shall have the capability to be interfaced via an Ethernet link (RJ45) and USB for connection
to a PC (optional and for configuration only) and a Modbus over Ethernet (Modbus TCP) for site control system.
The PC shall include programs / licensed software for displaying both temperature and fiber attenuation.

2021 Fiber Optic Linear Heat Detection Specification Page 1 of 4

15. All accessories, such as fittings, fastenings, sleeves, straps, staples, mounting clips, rings, junction boxes, relay
connection cables etc. which are required for interconnection with the fire alarm control panel shall be provided.

16. Sensor cable mounting kit shall be made of stainless-steel (dowel 1.4571/316Ti; clamp 1.4401/316) high grade
corrosion resistant stainless steel (corrosion class III) with European Technical Approval for low strength concrete
and shall comply with Fire Resistance Classification F120 / RWS 90 minutes (1350 °C curve).

17. The LHD instrument shall be able to operate in temperatures between -10 and +60 °C on a continual basis
without loss of performance.

18. The LHD system shall not be able to produce a source of ignition under any circumstance (inherently safe
operation) and should be internationally approved as such (ATEX and IECEx).

19. The designed configuration of the LHD system shall be internationally approved for fire detection as per UL 521 /
ULC S530, FM 3210 and by VdS according to EN 54-22.

20. Typical power consumption shall be less than 20 W (at 25 °C).

21. Laser source shall be based on a laser diode according to class 1M, as specified by EN 60825-1 (2000). The
average laser output power shall be less than 20 mW.

22. The LHD system shall have a proven SIL2 compliance.

Management & Visualization Software

1. Management software shall provide schematic asset visualization for quick orientation and instant status of all
configured LHD instrument.

2. Management software shall be integrated easily into the existing management platform over TCP protocols.

3. A Modbus TCP interface shall be included to transmit temperature and alarm status to existing control systems.

4. The Management Software Data Server shall be based on a Microsoft SQL database and shall collect data from
the connected LHD system(s) continuously.

5. The Management Software shall offer a system status overview, which lists all connected LHD instruments in a
clear graphical interface for alarms, fiber breaks and system status.

6. The actual sensor cable deployment shall be shown in the asset view as color-coded, temperature-related lines.
Operators shall have a real-time overview of the temperature conditions within the monitored infrastructure.

2021 Fiber Optic Linear Heat Detection Specification Page 2 of 4

DATA SHEET – Linear Heat Detector & Sensing Cable

Manufacturer: As per approved make

Type: OTDR based Fiber Optic Linear Heat Detection
Certified Range: 1 ch max. 10 km, 2 ch max. 8 km, 4 ch max. 7 km
Power Supply: 10 to 30 VDC / 25 W
Operating Temperature: -10 to 60 °C
Spatial Resolution: Configurable from 0.5 to 8.0 meters
Sampling Resolution: Configurable from 0.25 to 4.0 meters
Measurement Time: 10 to 30 seconds
Laser Safety: Class 1M, as specified by EN 60825-1 (2000)
Laser Power: < 20 mW average
LHD Instrument: LEDs and LCD display for power on / fault / alarm condition
Shall include 43 +1 integrated volt-free relay contacts
Expandable with up to 256 additional external volt-free relay contacts
PC Interface: Via RJ45 Ethernet and USB
SCADA Interface: Modbus TCP Slave
Mounting: 19” Rack Mounted or IP66 rated Wall Mount

Steel Sensor Cable Plastic Sensor Cable

Nominal Cable Diameter: 3.8 mm 4 mm
Max. Weight: 29 kg/km 17 kg/km
Max. Bending Radius: 80 mm 80 mm
Max. Crush resistance: 960 N/cm 100 N/cm
Max. tensile strength: 1100 N (long term) 1500 N (short term)
Operating Temperature: -40 to +85 °C (short term < one hour +150 °C)
Cable Functional Integrity: 2 hours at 750 °C as per IEC 60331-25
Fiber Optic Parameter: 50/125 µm Graded Index Multimode Fiber
Approvals: EN 54-22 / UL 521 / ULC S530 / ATEX / IECEx / FM 3210
Tested against: IEC 60331-25, IEC 60332-1/-2/-3-24, IEC 60754-1/-2, IEC 60793,
IEC 60794-1-2, IEC 61034-2

DATA SHEET – Management Software

Manufacturer: As per approved make.

Features: Graphical user interface
Central Microsoft SQL database
Color coded asset visualization
Alarm Management: Alarms shall be retrieved directly from the LHD instrument and visualized.

Administrative Functions: Multi-user management

Database backup/restore
Print functions
Export functions

2021 Fiber Optic Linear Heat Detection Specification Page 3 of 4

DATA SHEET – Cable Mounting Kit
M6 / 30 mm anchoring depth
Anchor load minimum 1.5 kN
Anchor with European Technical Approval – also for low strength concrete
Anchor Fire Resistance Classification F120 / RWS 90 min (1350 °C curve)
4 mm clamp, suited for the sensor cable

AP Sensing Point of Contact

Umair Aslam
Regional Sales & Support Engineer
AP Sensing Middle East
Umair.aslam@apsensing.com
+973 – 37747388

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